Causes

Other functions directly governed by the vestibular system include:

 

(1)       Auditory functions via the vestibulo-cochlear nerve

(2)       Visual functions

(3)       Muscle tone, balance and proprioception

            Smell, taste and touch are the only three modalities of human processing that are relatively unaffected by vestibular function, therefore the list of functions which may be irregular if the vestibular system is compromised is extremely diverse and expansive. Many of those irregularities will be mentioned in relation to the other systems supported by the vestibular system.

            The following problems may be part of the past history or present problems in children with irregular vestibular systems and could serve as indications to you that he or she may be showing difficulties with school work and/or behaviour because of vestibular problems:

 

∙          premature birth and a fairly long period of incubation after birth

∙          exposure to excessive movement or invasive sounds as a foetus or infant

∙          neglect (little handling and moving) during infancy

∙          repeated ear infections or severe ear infection

∙          tubes (grommets) having been inserted in the ears to drain excessive fluids

∙          excessive use of infant seat, jumper, swing and/or playpen, thus restricting or limiting natural movement

∙          avoidance of movement except as absolutely necessary

∙          avoidance of head movement

∙          head banging

∙          motion sickness (car, boat, airplane)

∙          avoidance of merry-go-rounds

∙          excessive watching of things spin, or excessive spinning of self

∙          dizziness or nausea caused by watching things move

∙          inability to read or write in cursive

∙          hearing problems

∙          inability to sustain listening without moving or rocking

∙          problem with balance (static or moving) and/or vertigo

∙          difficulty walking on uneven ground

∙          history of traumatic brain injury, shaken child syndrome, ear cuffing, etc.

∙          need to move fast

 

2.         Proprioception

            Proprioception refers to the brain’s unconscious sense of body-in-space. Essentially we use five systems to determine where our bodies are in relation to their environment and where various parts of our bodies are in relation to one another:

 

1.         The information received by the brain from the inner ear regarding the position of our heads, the pull of gravity, the speed and acceleration of our movement.

2.         The interpretation of messages received by our eyes about both the space and our position and posture

3.         The assorted information received by our brain from tactile, kinesthetic and proprioceptive sites located throughout the body

4.         The messages received by the brain through smell, a sense on which we unconsciously rely to discern direction and distance from objects and events in our environment

5.         The interpretation of the messages we have received through hearing, which also helps us orient to specific objects and events in our environment.

            If any of these functions are irregular, we either have a diminished sense of body-in-space or place greater reliance on another system (such as vision) to compensate which in turn causes us to use our eyes inefficiently for broader or higher level visual functions.

            Proprioception differs from kinesthesia in that kinesthesia is the sense of relative muscle, joint and tendon position in specific situations. Kinesthetic memory involves learning these positions and the sequence of shifts in these positions for rote, repeated movements (such as gymnastics). Proprioception is a dynamic sense, allowing continuous accommodations and adaptations to a shifting environment (such as in dance, or moving through a crowded room).

            The following issues are some of those that may occur in a person experiencing proprioceptive weaknesses and irregularities:

 

∙          A need as a baby to be held, swaddled, snuggled

∙          Unusual need to have physical contact with another person; clinging.

∙          Hysteria over hair washing or pulling tee shirts over the head

∙          Avoidance of eyes closed activities (such as Pin the Tail on the Donkey)

∙          Discomfort or disorientation in the shower

∙          Difficulty falling asleep and staying asleep

∙          Sleep walking

∙          Falling out of bed

∙          Feeling as if he/she is floating in space or tipping in space while in bed

∙          Extreme restlessness while sleeping

∙          Difficulty getting up and moving after sleep

∙          Need for heavy covers or clothing or a back pack to feel grounded

∙          Need to have the light on to sleep

∙          Avoidance of team sports

∙          Aversion to crowds

∙          Preference for and greater skill in swimming than in other sports

∙          Clumsiness, tripping over own feet, bumping into things

∙          Swinging between pieces of furniture

∙          Unusual degree of stretching and yawning

∙          Difficulty grasping mathematical concepts

∙          Inability to accept physical (and social) boundaries

 

3.         Differentiation

            Differentiation of response is the inhibition of primitive reflexes and more. It is the ability to direct one part of the body to move according to plan while all other parts remain still. It is the precursor to the development of lateralisation, and helps the brain establish specialised centres.

            Children with immature differentiation may demonstrate overflow movements. This means that when one part of the body (e.g. a hand) moves, other parts move as well. Immature differentiation also accompanies an apparent weakness in kinesthetic memory (the memory that the muscles have for movement), since overflow movement defocuses the brain’s processing of the intended movement. Such children may not realise that they are kicking, knocking over, or in other ways disturbing people and objects in their environment. They disclaim responsibility for these actions and may be viewed as liars. It is usually evident that there was no malice in their actions. However, after prolonged periods of receiving blame and punishment for these problems, an individual may begin to exhibit the behaviours that his/her peers seem to expect. It becomes easy to see how irregularities in differentiation can cause poor academic learning and also serious social problems.

            The following are some of the issues that may occur in a person experiencing difficulties with differentiation:

 

∙          overflow movement to the head or jaw when eyes are tracking (e.g. reading)

∙          overflow movement to the opposite hand when one hand is engaged

∙          overflow movement to the legs when one hand is engaged

∙          tics that involve more than just the eyes, including Tourette’s Syndrome

∙          inability to sort out each finger for fine-motor coordination

∙          overflow movement to the tongue and/or mouth when concentrating

∙          knocking things over at the table

∙          startle reactions

∙          difficulty ‘turning off’ obsessive compulsive thoughts and actions

 

4.         Lateralisation

 

            Lateralisation refers to development of lateral dominance (right or left eye, ear, hand, leg) and development of specialised centres and functions in the left and right brain hemispheres. The right side of the body sends messages to and is controlled by the left side of the brain, and the left side of the body by the right side of the brain. Differentiation is a precursor to the development of lateralisation. The ability to cross one’s midline is also a necessary component for mature lateralisation.

 

            Most people develop unilateral cerebral dominance - that is their dominant eye, ear, hand and leg are on the same side of the body. Approximately 20% of the population has mixed dominance or other irregularities in the development of dominance. Those irregularities of dominance that are the most difficult to resolve without therapeutic help involve alternating reliance on one side or the other without conscious decision to do so. Such children will use first one hand when writing and then the other, for example. This causes instability in perception and performance. Immaturities and irregularities in lateralisation can cause perceptual, organisational and performance problems in all areas of life.

 

            The following are issues that may occur in a person experiencing difficulties with lateralisation:

 

∙          Delayed decision of lateral dominance

∙          Tendency to scatter and misplace objects in personal space

∙          Extreme rotation of writing or reading surface

∙          Unusual tip of the head while writing (30-40 degree tip usually indicates crossed dominance between eye and hand)

∙          Difficulty perceiving left and right sides of objects and letters

∙          Uncertainty about personal left and right body sides

∙          Tendency to move toward the non-dominant hand in motor activities

∙          Need to rotate surfaces to complete motor activities that cross the midline

∙          Difficulty making decisions

∙          Difficulty accepting a change in a rule or decision once it is made.

∙          Excellent batting in cricket or baseball but difficulty with many other sports.

 

 

5.         The visual sense

 

            Vision exerts strong and sometimes supreme command over our other senses, as optical illusions demonstrate, and it exercises similar effects on our posture and locomotion (movement). With one’s eyes closed, standing soon becomes difficult, and, unless by luck, we would find it impossible to thread a needle.

 

            Most people think that if a child’s vision is 20/20 then everything is fine. This is usually tested by a nurse with a Snellen chart (containing letters of different sizes that have to be identified at a certain distance). What needs to be understood is that vision is more than just clarity. It also includes binocular coordination, speed accommodation, vertical movement and other visual functions necessary to visualise, understand and apply the information that comes through the eyes. Children may not have these abilities in spite of having ‘good eyesight’ and this results in learning problems. Difficulties arise because vision impaired children rarely report symptoms. They think everyone sees the same as they do. Our two eyes are supposed to work together - to perform as one entity. This is a skill that must be acquired through use during the preschool years. Not all children adequately develop visual skill and this can interfere with comprehension, the ability to perceive spatial relations, and the ability to concentrate. For example, there may be visual discomfort or distortions of the text while reading. This reduces close attention to details and sustained mental effort. As a result, a child will be easily distracted. The signs of inattention are not only observable, but also many times interpreted (or misinterpreted) simply as Attention Deficit Disorder. The following are two vital functions of vision which may impair learning.

 

Binocular functions

 

            Binocular functions refer to the ability of the eyes to coordinate their activity so that we can merge the visual fields of both eyes into one distinct image. The most commonly observed aspects of binocular functions include convergence (the ability of the two eyes to team and focus on the same object), and accommodations (the ability of the eyes to shift their focus from near point to far point or vice versa). Each eye can have normal acuity (20/20 vision) but unless the eyes team, visual functions are impaired.

 

            The following are issues that may occur in a person experiencing difficulties with binocular functions:

 

∙          Difficulty going down stairs

∙          Poor eye-hand coordination

∙          Pain, watering, discomfort when required to perform visual work

∙          Inability to read without losing place

∙          Rubbing eyes after use

∙          Frequent headaches after visual work

∙          Frequent stomach aches after visual work

∙          Difficulty copying from the board

∙          Generalised light sensitivity (photophobia)

∙          Poor three-dimensional perception

∙          Difficulty in sustaining eye contact

 

Ocular motility

 

            The oculomotor system is the system that controls eye movement. The function of this system is to bring the fovea of the retina (the region where vision is sharpest) into alignment with a visual target of interest and to maintain this alignment. In such a seemingly simple movmeent such as the control of the eye, there are distinctive movement: rapid search or saccadic eye movements, movements governed by the semicircluar canals (the vestibulo-ocular reflex) and smooth pursuit tracking (ocular motility).

 

            Saccadic eye movements represent a scanning of the field of view - a search for targets. We are constantly shifting our eyes from position to position from one object to another, often without a head movement. There are alternate periods of fixation and shift, fixation and shift, etc. These eye movements are enormously rapid and is the fastest movement the body performs.

 

            Vestibulo-ocular reflex is a reponse that makes it possible to maintain visual fixation on a target no matter how the head is moved. For example, if you are looking at this page and you turn your head, your eyes will turn in the opposite direction so that you do not lose focus. This is made possible by input from the vestibular organ that generates and equal but oppositely directed eyemovement that corresponds to the speed of the head movement.

 

            Smooth pursuit tracking is known as ocular motility (frequently called visual tracking). This voluntary eye movement is used for tracking an object (a fly or an airplane, for example) as it moves in the visual field. It requires the eyes to move smoothly through all planes of the visual field without blurring or loss of image. This ability is dependent on the muscles and cranial nerves that service the eyes, as well as on the vestibular system which provides information and regulation. It is very important to ease of reading and writing.

 

            The following are issues that may occur in a person experiencing difficulties with ocular motility:

 

∙          Inability to hold head still while tracking

∙          Dizziness and/or nausea when required to track

∙          pain, watering, discomfort when required to track

∙          Reporting that objects blur or are lost in the field of vision when required to track

∙          Rubbing eyes after use

∙          Frequent headaches after visual work

∙          Frequent stomach aches after visual work

∙          Eyes move with a jerky or bouncy pursuit when tracking

∙          Eyes stop tracking an object that continues to move

∙          Overflow movements to other parts of the face or body when attempting to track

∙          Inability to read aloud, although can grasp meaning from silent reading.

 

6.         Interhemispheric integration

 

            Interhemispheric integration refers to the communication between the left and right cerebral hemispheres. To function efficiently, we need to integrate information from various specialised centres and to coordinate a planned response. Efficient binocular functions require interhemispheric integration of the two hemispheres.

 

            Children who are cross dominant (e.g. right handed but left eyed) require very efficient interhemispheric integration to compensate for additional demands to integrate information from two competing or differing perceptual and operational modes. Sucking and crawling are two activities of infancy that assist in developing interhemispheric integration. Furthermore, interhemispheric integration is interdependent on differentiation and lateralisation.

 

            The following are issues that may occur in a person experiencing difficulties with interhemispheric integration:

 

∙          Delayed language acquisition

∙          Difficulty understanding directions

∙          Significant difficulty with reading

∙          Problems of word finding

∙          Perseverative behaviours

∙          Lack of crawling in infancy

∙          Weak or limited sucking in infancy

∙          Delayed accomplishment of tying shoe laces

∙          Immature dressing skills (e.g. pulls on pants, two legs together, needs help getting arms into sleeves)

∙          Great difficulty learning to swim; to pedal a bicycle

∙          Difficulty with organisational skills

∙          Diminished concept of consequences

∙          Impulsivity

 

 

The root cause of your child’s problems may be due to problems in one or more of these systems

 

This we refer to as neurodevelopmental delays or concerns

 

            The development of the neurological pathways in the brain that make the integration of sensory information possible, increases as children grow. If children do not have the opportunity to do activities that correspond with each stage of development, then they will not reach their neurological potential. Examples of these necessary activities are using both eyes at the same time, recognising and distinguishing symbols, understanding words, touching things, crawling, walking upright, running, swinging arms, skipping, other activities that require coordination and balance, communicating with speech and picking up and manipulating small objects.

 

            Sensory input and motor activities develop the proper sequence of neurological functioning and are essential for the development of learning. Learning is a sensory process that must be reinforced by motor functioning. If input is nonexistent, limited, or confused, the sensory pathways will not develop correctly. The person has to begin again with activities and sensory inputs that have proven beneficial in promoting effective neurological organisation from early infancy on.

 

            Children who have not reached the peak of their neurological development find it difficult to do the required classroom work. Children with immature nervous systems often seem to be misbehaving, or not making an effort. They may not have the capacity to meet these challenges yet.

It is also possible that other influences may be contributing to the problems

 

We follow a truly holistic approach to helping children overcome barriers to learning. So we also consider nutritional and environmental factors.

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